The medical event at a Wairarapa school where students and staff had to be treated by paramedics on Friday was caused by hot compost that was delivered to a neighbouring property, and a wind shift.
Wairarapa Area Commander Inspector Scott Miller said the fresh compost, which was heated to 80 degrees Celsius, caused the strong sulphur smell that people experienced at South End School.
The supplier of the compost, who hadn’t experienced this issue in 50 years in the business, confirmed to police that the product can cause a strong sulphur smell.
“What we have confirmed, just after 1pm on Friday, one of the neighbouring properties next to the school, had a type of fertiliser, compost really, delivered,” Inspector Miller said.
“That compost was fresh and as part of that, was actually hot, part of the process for compost is to heat it up to 80 degrees Celsius.”
“That creates a sulphur smell, that sulphur smell can be very strong.”
At roughly 1.20pm, the first children began to feel ill as a result of the smell.
Inspector Miller said that most of the children who felt sick were at the rear of the school, closest to the delivery of compost.
He added that there were unlikely to be any lingering effects for the children who felt most ill.
Emergency services were called to South End School on Friday after reports of an unpleasant smell.
Paramedics treated 40 other people, children and adults, with minor symptoms after being called to South End School.
Over 100 people also had to go through a decontamination process.
There were reports of a plane flying overhead at the time, but police ruled that out as the cause.